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Abstract:

There is provided a collective printed circuit board including a
plurality of printed circuit boards each having a mounting unit on which
a semiconductor element is mounted at an upper-surface central portion,
and a frame having a plurality of through holes having sizes to surround
the mounting portion. Upper-surface peripheral edge portions of the
printed circuit boards and a through-hole peripheral portion of the frame
are bonded to each other such that the mounting units are exposed from
the through holes.

Claims:

1. A collective printed circuit board comprising: a plurality of printed
circuit boards each having a mounting portion, on which a semiconductor
element is mounted, at an upper-surface central portion; and a frame
having a plurality of through holes having sizes to surround the mounting
portions, wherein upper-surface peripheral edge portions of the printed
circuit boards and a through-hole peripheral portion of the frame are
bonded to each other such that the mounting portions are exposed from the
through holes.

2. The collective printed circuit board according to claim 1, wherein a
plurality of connection conductors penetrating both major surfaces of the
frame are formed on a peripheral portion of the through hole of the
frame, a plurality of frame connection pads formed by parts of a
conductor layer formed on the printed circuit board are formed on
upper-surface peripheral edges of the printed circuit boards, and the
corresponding connection conductor and the frame connection pad are
electrically connected to each other.

3. The collective printed circuit board according to claim 1, wherein a
semiconductor element is mounted on the mounting portion of the printed
circuit board.

4. The collective printed circuit board according to claim 1, wherein a
sealing resin is filled in any one or both of a gap between the printed
circuit board and the frame and a gap between the printed circuit board
and the semiconductor element mounted on the printed circuit board.

5. The collective printed circuit board according to claim 1, wherein an
electronic part having a height enough to project from an upper surface
of the frame is mounted on an upper surface of the printed circuit board
in the through hole, and a second printed circuit board having an opening
or a recessed portion adapted to house a portion projecting from the
frame of the electronic part at a position corresponding to the
electronic part is bonded to the upper surface of the frame.

6. The collective printed circuit board according to claim 1, wherein at
least one of a plurality of through holes and trenches is formed at a
position corresponding to a bonding portion between the frame and the
printed circuit board, and a second printed circuit board having a second
through hole at positions corresponding to the through holes and the
trenches is bonded to the upper surface of the frame without completely
closing the through hole.

7. The collective printed circuit board according to claim 1, wherein a
surface opposing the bonding portion between the frame and the printed
circuit board has an external connection pad to which an external
electric circuit board is connected.

8. The collective printed circuit board according to claim 1, further
comprising a second printed circuit board bonded to an upper surface of
the frame to close the opening of the frame, wherein a third printed
circuit board having a layer configuration or a material different from
that of the frame is bonded between the printed circuit board and the
second printed circuit board inside the opening.

9. The collective printed circuit board according to claim 8, wherein the
frame is a buildup multi-layered board, and the third printed circuit
board is a through hole board.

10. The collective printed circuit board according to claim 8, wherein a
heat conductivity of the third printed circuit board is higher than a
heat conductivity of the frame.

11. The collective printed circuit board according to claim 1, further
comprising a second printed circuit board bonded to an upper surface of
the frame through a solder bump to cover the opening of the frame,
wherein a flow path for a sealing resin is formed from the upper surface
of the frame or an upper surface of the second printed circuit board to a
portion between the frame and the second printed circuit board and a
portion between the printed circuit board and the frame, and the sealing
resin flows through the flow path from the upper surface of the frame or
the upper surface of the second printed circuit board to the portion
between the frame and the second printed circuit board and the portion
between the printed circuit board and the frame to perform filling of the
sealing resin.

12. The collective printed circuit board according to claim 11, wherein
the flow path is formed by at least one of a trench, a through hole, and
a convex stripe.

Description:

BACKGROUND OF THE INVENTION

[0001] (1) Field of the Invention

[0002] The present invention relates to a collective printed circuit board
obtained by bonding a plurality of small printed circuit boards each
having a mounting unit on which a semiconductor element is mounted to a
frame having through holes surrounding the mounting units.

[0003] (2) Description of Related Art

[0004] Conventionally, in order to simultaneously manufacture a large
number of small printed circuit boards to mount semiconductor elements
thereon as disclosed in Unexamined Patent Publication No. 1998-189829,
Unexamined Patent Publication No. 2001-210954, and Published Japanese
Translation No. 2001-511946 of the PCT International Publication (U.S.
Pat. No. 6,329,606), a collective printed circuit board is used. In the
collective printed circuit board, a plurality of small printed circuit
boards are integrally arranged in vertical and horizontal directions such
that cutting areas are formed between the small printed circuit boards.
On each of the printed circuit boards, after semiconductor elements are
mounted through, for example, solder bumps, sealing is performed with a
sealing resin. Thereafter, cutting is performed along the cutting areas
to simultaneously manufacture electronic devices having semiconductor
elements mounted on the printed circuit boards.

[0005] In the collective printed circuit board, an electric testing or an
appearance check for the printed circuit boards is performed before the
semiconductor elements are mounted, and a printed circuit board
determined as a defective product is marked, or position information of
the defective printed circuit board is recorded. In this manner, a
semiconductor element can be avoided from being mounted on the printed
circuit board determined as a defective product.

[0006] However, in recent years, with advances in miniaturization and
multi-layering of circuits of collective printed circuit boards,
processes become complicated and difficult, a yield of printed circuit
boards in a collective printed circuit board tends to decrease. For this
reason, the number of electronic devices that can be simultaneously
manufactured from one collective printed circuit board decreases, a
problem such as deterioration of operating efficiency and an increase in
cost is posed.

[0007] In a conventional collective printed circuit board, when sealing is
performed with a sealing resin, after the sealing resin is heated to be
hardened, the temperature of the sealing resin is returned to a room
temperature. At this time, the sealing resin thermally contracts largely
more than the printed circuit board. As a result, the printed circuit
board is warped such that an upper surface side of the printed circuit
board is concaved. This is because a thermal expansion coefficient of the
sealing resin is larger than a thermal expansion coefficient of the
printed circuit board. When the warpage is large, electronic devices
formed by cutting the collective printed circuit board are difficult to
be mounted on another circuit board.

SUMMARY OF THE INVENTION

[0008] The present invention has been proposed in consideration of the
above problems. More specifically, a main object of the present invention
is to provide a collective printed circuit board that can increase a
yield of printed circuit boards in a collective printed circuit board,
prevent the number of electronic devices that can be simultaneously
manufactured from one collective printed circuit board from decreasing,
and solve problems such as deterioration of operating efficiency and an
increase in cost.

[0009] It is another object of the present invention to provide a
collective printed circuit board that can suppress warpage of an
electronic device caused by a thermal processing step in sealing by a
sealing resin, therefore, mount a semiconductor element on a flat printed
circuit board, and stably supply the electronic device that can be
preferably mounted on another circuit board.

[0010] According to the present invention, there is provided a collective
printed circuit board including a plurality of printed circuit boards
each having a mounting unit on which a semiconductor element is mounted
at an upper-surface central portion, and a frame having a plurality of
through holes having sizes to surround the mounting units, wherein
upper-surface peripheral edge portions of the printed circuit boards and
a through-hole peripheral portion of the frame are bonded to each other
such that the mounting units are exposed from the through holes.

[0011] According to the present invention, since one collective printed
circuit board is formed by independently bonding a plurality of printed
circuit boards to a frame, only non-defective printed circuit boards can
be selected and bonded to the frame. In this manner, a collective printed
circuit board in which printed circuit boards having a very high yield
are arranged can be formed. Thus, the number of electronic devices that
can be simultaneously manufactured from one collective printed circuit
board can be prevented from decreasing, and the problem such as
deterioration of operating efficiency or an increase in cost can be
solved.

[0012] According to the present invention, the rigidity can be improved by
the frame, the upper-surface peripheral edge portions of the printed
circuit boards are bonded to lower surfaces of the peripheral portions of
the through holes formed in the frame such that semiconductor element
mounting units are exposed from the through holes. For this reason, an
amount of sealing resin can be minimized to suppress the upper-surface
sides of the printed circuit boards from being deformed into a concave
shape. In this manner, there can be provided a collective printed circuit
board in which semiconductor elements are mounted on flat printed circuit
boards and that can stably supply electronic devices that can be
preferably mounted on another circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIGS. 1A and 1B are a sectional view and an upper view showing an
embodiment in a collective printed circuit board according to the present
invention;

[0014] FIGS. 2A and 2B are a sectional view and an upper view showing an
example of a printed circuit board in the collective printed circuit
board according to the present invention;

[0015] FIGS. 3A and 3B are a sectional view and an upper view showing an
example of a frame in the collective printed circuit board according to
the present invention;

[0016] FIG. 4 is a sectional view for explaining an example of an
embodiment in the collective printed circuit board according to the
present invention;

[0017] FIG. 5 is a sectional view for explaining an example of the
embodiment in the collective printed circuit board according to the
present invention;

[0018] FIG. 6 is a sectional view for explaining an example of the
embodiment in the collective printed circuit board according to the
present invention;

[0019] FIG. 7 is a sectional view for explaining an example of the
embodiment in the collective printed circuit board according to the
present invention;

[0020] FIG. 8 is a sectional view for explaining an example of the
embodiment in the collective printed circuit board according to the
present invention;

[0021] FIG. 9 is a sectional view for explaining an example of the
embodiment in the collective printed circuit board according to the
present invention;

[0022] FIG. 10 is a schematic sectional view showing an example of another
embodiment in the collective printed circuit board according to the
present invention;

[0023] FIG. 11 is a schematic sectional view showing an example of still
another embodiment in the collective printed circuit board according to
the present invention;

[0024] FIG. 12 is a schematic sectional view showing an example of another
embodiment of the present invention;

[0025] FIG. 13 is a schematic sectional view showing an example of still
another embodiment of the present invention; and

[0026] FIG. 14 is a schematic sectional view showing another example of
still another embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0027] An example of an embodiment of a collective printed circuit board
according to the present invention will be described below with reference
to FIGS. 1 to 9. As shown in these drawings, a collective printed circuit
board 30 of this example is mainly configured by a printed circuit board
10 and a frame 20.

[0028] As shown in FIG. 1, a plurality of small printed circuit board 10
to mount a semiconductor element 15 thereon are bonded to a lower surface
of the frame 20 to support the printed circuit boards 10.

[0029] Each of the printed circuit boards 10 includes, as shown in FIGS.
2A and 2B, for example, an insulating substrate 1 obtained by stacking
insulating layers 1b on upper and lower sides of an insulating plate 1a,
respectively, conductive layers 2 formed on the insulating plate 1a and
the insulating layer 1b, and a solder resist layer 3 used as a protective
layer. A mounting portion 8 on which the semiconductor element 15 is
mounted is formed on an upper-surface central portion of the printed
circuit board 10.

[0030] The insulating plate 1a constituting the insulating substrate 1 is
made of an electric insulating material obtained by impregnating a
thermosetting resin such as an epoxy resin or a bismaleimide triazine
resin in glass fiber sheet. In the insulating plate 1a, a plurality of
through holes 4 vertically penetrate the insulating plate 1a are formed
by drilling. A through hole conductor 2a is formed on a side wall of each
of the through holes 4 to electrically conduct the upper and lower
conductive layers 2 of the insulating plate 1a.

[0031] The insulating layers 1b stacked on the upper and lower sides of
the insulating plate 1a is made of an electric insulating material
containing thermosetting resin such as an epoxy resin or a polyimide
resin. A plurality of via holes 5 that penetrates the insulating layers
1b from the upper surface to the lower surface thereof are formed by
laser processing. Via conductors 2b are filled in the via holes 5. In
this manner, the upper and the lower conductive layers 2 of the
insulating layer 1b are electrically connected to each other.

[0032] The conductive layers 2 are wires formed by copper-plated layers or
a metal such as copper foil by using a known subtractive method or a
semi-additive method, for example. The conductive layers 2 function as
paths that supply an electric power to or input/output a signal to/from
the semiconductor element 15.

[0033] The solder resist layer 3 is made of a thermosetting resin such as
an acrylic modified epoxy resin having photosensitivity, and has openings
3c, 3d, and 3e that partially expose the conductive layers 2. The solder
resist layer 3 keeps the electric insulativity of the conductive layers 2
preferable, and has a function of protecting the conductive layers 2.

[0034] A part of the conductive layers 2 exposed from the opening 3c of
the solder resist layer 3 at the mounting portion 8 forms a semiconductor
element connection pad 6. An electrode 16 of the semiconductor element 15
is connected to the semiconductor element connection pad 6 through, for
example, a solder bump. On the lower surface, a part of the conductive
layers 2 exposed from the opening 3d of the solder resist layer 3 forms
an external connection pad 9. The external connection pad 9 is connected
to a wiring conductor of an external electric circuit board through, for
example, a solder ball. Furthermore, at the upper-surface peripheral edge
portion of the printed circuit board 10, a part of the conductive layers
2 is exposed from the opening 3e of the solder resist layer 3. The part
exposed from the opening 3e forms a frame connection pad 7 to be
electrically connected to the frame 20. The frame connection pad 7 is
connected to a connection conductor 22 of the frame 20 (will be described
later).

[0035] The frame 20, as shown in FIG. 3A, includes an insulating plate 21,
the connection conductor 22 that penetrates the insulating plate 21, and
solder resist layers 23 formed on the upper and lower surfaces of the
insulating plate 21. The frame 20 functions as a supporter that supports
the plurality of printed circuit boards 10 in a predetermined alignment,
and has a through hole 24 having a size to surround the mounting portion
8 of the printed circuit board 10 at a position corresponding to the
alignment of the supported printed circuit boards 10. Around the through
hole 24, the connection conductor 22 is formed at a position
corresponding to the frame connection pad 7 described above.

[0036] The insulating plate 21 is made of an electric insulating material
obtained by impregnating a thermosetting resin such as an epoxy resin or
a bismaleimide triazine resin in glass fiber sheet. The through hole 24
is formed by, for example, routing. A plurality of through holes 25 to
form the connection conductor 22 are formed around the through hole 24 by
drilling. The insulating plate 21 has a function as a core material that
strengthens the frame 20. The insulating plate 21 preferably has a
thickness of 0.3 mm or more to keep rigidity to suppress warpage
occurring in a sealing operation after the semiconductor element 15 is
mounted on the collective printed circuit board 30 of this example.

[0037] The connection conductor 22 is formed by, for example, copper
plating, and is formed by coating a metal such as copper on side walls of
the through holes 25 by a plating method or the like. The connection
conductor 22 is connected to the frame connection pad 7 of the printed
circuit board 10 to make it possible to mount another electronic part, a
radiator plate, or the like on the upper surface of the frame 20 to
electrically connect the electronic part or the radiator plate to the
conductive layers 2 of the printed circuit board 10.

[0038] The solder resist layers 23 is made of an electric insulating
material containing thermosetting resin such as an epoxy resin or a
polyimide resin, and has openings 23a and 23b that expose the upper end
and the lower end of the conductive conductor 22.

[0039] The plurality of printed circuit boards 10 are bonded to the lower
surface of the frame 20 such that the mounting portion 8 is exposed in
the through hole 24 and the frame connection pad 7 and the connection
conductor 22 are electrically connected to each other, thereby forming
the collective printed circuit board 30 shown in FIG. 1. The printed
circuit boards 10 and the frame 20 are bonded to each other such that the
plurality of connection conductors 22 formed on a peripheral portion of
the through hole 24 of the frame 20 and the plurality of corresponding
frame connection pads 7 formed on upper-surface peripheral edges of the
printed circuit boards 10 are bonded through a bonding material 35. As
the bonding material 35, for example, a solder is used. A solder bump
(not shown) is formed on the frame connection pad 7 by a printing method,
and the corresponding connection conductor 22 is placed on the solder
bump and subjected to a reflow process in a condition of 220 to
260° C. in a state in which the frame 20 and the printed circuit
board 10 overlap so as to bond the printed circuit boards 10 to the frame
20.

[0040] As the bonding material 35, in addition to the solder described
above, an anisotropic conductive material such as an anisotropic
conductive film or an anisotropic conductive paste may be used. This is
obtained by mixing conductive particles of a gold-plated resin or the
like in a thermosetting resin such as an epoxy resin or a synthetic
rubber resin. An anisotropic conductive material is placed on the frame
connection pad 7, the corresponding connection conductor 22 is placed on
the anisotropic conductive material, and the connection conductor 22 and
the printed circuit board 10 are bonded to each other by
thermocompression in conditions of 100 to 200° C. and 3 to 5 MPa
such that the frame 20 and the printed circuit board 10 overlap.

[0041] The printed circuit board 10 is subjected to an electric testing
and an appearance check before the printed circuit board 10 is bonded to
the frame 20, and only non-defective printed circuit boards 10 are bonded
to the frame 20. In this manner, the collective printed circuit board 30
having the printed circuit boards 10 formed at a very high yield can be
obtained. Thereafter, in the collective printed circuit board 30, the
semiconductor element 15 is mounted on the mounting portion 8 of each of
the bonded printed circuit boards 10. In order to mount the semiconductor
element 15, for example, a solder ball is mounted on the semiconductor
element connection pad 6, and the electrode 16 of the corresponding
semiconductor element 15 is overlapped on the solder ball and subjected
to a reflow process in a condition of about 220 to 260° C., i.e.,
the electrode 16 and the solder ball are connected to each other by a
flip chip technique.

[0042] After the semiconductor element 15 is mounted, a sealing resin made
of a thermosetting resin is injected into the through hole 24.
Thereafter, the semiconductor element 15 is sealed by thermally curing
the sealing resin. The injection of the resin is performed by a printing
method that a resin is applied by using, for example, a printing mask. At
this time, according to the collective printed circuit board 30 of the
present invention, the side wall of the through hole 24 has a role of
preventing the sealing resin from flowing out. For this reason, a metal
mold for sealing resin injection that is required in the past is not
required. When the size of the through hole 24 is minimized to seal the
through hole 24, an amount of sealing resin to be injected can be
reduced. The sealing resin is thermally cured at a temperature of 150 to
250° C. At this time, since the collective printed circuit board
30 is increased in rigidity by the frame 20, the printed circuit board 10
can be suppressed from being deformed by thermal contraction of the
sealing resin.

[0043] Upon completion of the sealing operation, a different electronic
part or a radiator plate are mounted on the frame 20, for example. A mode
in which the different electronic part is further mounted on the frame 20
is called so-called PoP (Package on Package). An explanation of the
embodiment will be made with reference to FIG. 4. In this case, the
connection conductor 22 exposed from the openings 23a formed in the frame
20 and an electrode 42 of a different electronic part 41 are bonded to
each other through a conductive bonding material such as a solder to make
it possible mount the different electronic part 41 and printed circuit
board 10 that are electrically connected to each other. When a metal
radiator plate is mounted on the frame 20, the radiator plate and the
connection conductor 22 are bonded to each other through a conductive
bonding material such as a solder. The radiator plate is preferably
connected to the ground potential.

[0044] After the semiconductor element 15 and the different electronic
part are mounted on the collective printed circuit board 30, independent
electronic devices cut by, for example, a dicing apparatus along cutting
areas between the printed circuit boards 10 are obtained.

[0045] As described above, in the collective printed circuit board 30,
only the non-defective printed circuit boards 10 are selected and bonded
to the frame 20 to make it possible to prevent the number of electronic
parts that can be simultaneously manufactured from one collective printed
circuit board 30 from decreasing and to solve a problem such as
deterioration of operating efficiency and an increase in cost. The
rigidity is improved by the frame 20, and a sealing resin used when the
semiconductor element 15 mounted on the printed circuit board 10 is
sealed is minimized to make it possible to suppress deformation caused by
a difference in thermal expansion between the sealing resin and the
printed circuit board 10. In this manner, the collective printed circuit
board 30 in which the semiconductor element 15 is mounted on the flat
printed circuit board 10 and that can stably supply an electronic device
that can be preferably mounted on another circuit board can be provided.

[0046] The present invention is not limited to an example of the
embodiment described above. For example, in an example of the embodiment
described above, the frame 20 includes the connection conductor 22, and
the different electronic part and a radiator plate are mounted on the
frame 20 to be electrically connected to the connection conductor 22.
However, the frame 20 need not always include the connection conductor
22, and the different electronic part and the radiator plate need not be
always mounted on the frame 20.

[0047] Furthermore, the collective printed circuit board of the present
invention can also be applied to an electronic device in which, for
example, a capacitor and a resistor are built. The embodiment will be
described with reference to FIG. 5. In this example, a printed circuit
board 56 in which, for example, passive parts 54a and 54b are
incorporated is bonded to the frame 20. The passive part 54a is buried in
the printed circuit board 56. The passive part 54b is mounted on an upper
surface of the printed circuit board 56 at a position corresponding to
the frame 20.

[0048] A recessed portion in which the passive part 54b can be housed at a
position corresponding to the passive part 54b is formed in the frame 20.
A frame connection pad 55 of an upper-surface end portion of the printed
circuit board 56 and the connection conductor 22 exposed from an opening
23b are bonded to the frame 20 through a conductive bonding material.
Thereafter, a semiconductor element 53 is mounted on an upper surface of
the printed circuit board 56 by the flip chip technique described above.
Furthermore, a sealing resin is injected into the through hole 24 of the
frame 20, and a metal radiator plate 51 is bonded to the frame 20 to
close up the through hole 24. At this time, the radiator plate 51 is
preferably electrically connected to a ground conductor of the printed
circuit board 56 through the connection conductor 22 of the frame 20. The
semiconductor element 53 and the radiator plate 51 are preferably
thermally connected to each other through a connection layer 52 such as
an epoxy resin containing, for example, thermal grease or thermally
conductive particles. By employing the mode, electronic devices each
having a passive part and a small warpage can be efficiently and stably
provided at a high yield.

[0049] In the example described above, a sealing resin is entirely filled
in the through hole 24 of the frame 20 to which the printed circuit board
10 is bonded. However, the sealing resin may be filled in a bonded
portion that is required to be reinforced with a resin. The embodiment
will be described with reference to FIG. 6. A frame connection pad 63 on
an upper-surface end portion of a printed circuit board 61 and the
connection conductor 22 exposed from the opening 23b on a lower-surface
side of the frame 20 are bonded to each other through a conductive
bonding material. Thereafter, semiconductor elements 62a and 62b are
mounted on an upper surface of the printed circuit board 61 through a
conductive bonding material. A sealing resin 66 made of a thermosetting
resin is injected by using, for example, an air nozzle into a bonding
portion between the printed circuit board 61 and the frame 20 or a
bonding portion between the printed circuit board 61 and the
semiconductor elements 62a and 62b. At this time, when an enclosure to
prevent the sealing resin 66 from flowing is formed around the
semiconductor element by a solder resist, the sealing resin can be easily
injected. When the sealing resin 66 is thermally cured at a temperature
of 150 to 250° C., the sealing resin 66 filling is completely
finished. A second printed circuit board 64 is bonded to the frame 20
through a conductive bonding material such that an electrode 65 on a
lower-surface end portion of the second printed circuit board 64 is
connected to a connection conductor 22 exposed from the opening 23a on an
upper-surface side of the frame 20. In this manner, when an amount of
sealing resin filled in the through hole 24 is reduced, warpage of an
electronic device 60 caused by a difference in thermal expansion
coefficient between the printed circuit board described above and the
sealing resin can be more suppressed.

[0050] The collective printed circuit board according to the present
invention can also be applied to an electronic device in which
high-profile electronic parts are mounted on, for example, a printed
circuit board. The embodiment will be described with reference to FIG. 7.
A frame connection pad 73 on an upper-surface end portion of a printed
circuit board 71 and the connection conductor 22 exposed from the opening
23b on a lower-surface side of the frame 20 are bonded through a
conductive bonding material. Thereafter, an electronic part 72 is mounted
on an upper surface of the printed circuit board 71 through a conductive
bonding material. A second printed circuit board 74 is bonded to the
frame 20 through a conductive bonding material such that an electrode 75
on a lower-surface end portion of the second printed circuit board 74 is
connected to the connection conductor 22 exposed from the openings 23a on
an upper-surface side of the frame 20. At this time, in the second
printed circuit board 74 at a position corresponding to the electronic
part 72, an opening 76 that can house the electronic part 72 projecting
from frame 20 is formed. The opening 76 is formed by a router device or
the like. By employing the mode, the electronic part 72 can be avoided
from colliding with the second printed circuit board 74, and electronic
devices 70 can be efficiently and stably provided at a high yield without
increasing the thicknesses of the electronic devices 70. Furthermore, the
present invention can also be applied to an electronic device in which a
variable resistor is mounted as the electronic part 72 in the example and
that can operate a variable part by using the opening 76.

[0051] The collective printed circuit board according to the present
invention can also be applied to an electronic device in which a flux
residual adhering to the printed circuit board on the inside of, for
example, the electronic device needs to be efficiently cleaned up. The
embodiment will be described with reference to FIG. 8. A frame connection
pad 83 on an upper-surface end portion of a printed circuit board 81 and
the connection conductor 22 exposed from the opening 23b on a
lower-surface side of the frame 20 are bonded to each other through a
conductive bonding material. Thereafter, a semiconductor element 82 is
mounted on an upper surface of the printed circuit board 81 through a
conductive bonding material. A second printed circuit board 84 is bonded
to the frame 20 through a conductive bonding material such that an
electrode 85 on a lower-surface end portion of the second printed circuit
board 84 is connected to the connection conductor 22 exposed from the
openings 23a on an upper-surface side of the frame 20. When the second
printed circuit board 84 is bonded to the frame 20, the through hole 24
is partially opened not to completely close the through hole 24, and the
through hole 24 is used as an injection/discharge port of a cleaning
liquid for removing a flux residual. At this time, in the frame 20, in a
position corresponding to a bonding portion between the printed circuit
board 81 and the second printed circuit board 84, a plurality of through
holes 86 and a plurality of trenches 87 are formed. In the second printed
circuit board 84, second through holes 88 are formed at positions
corresponding to the through holes 86 and the trenches 87. The through
holes 86 are formed by a drilling device and have diameters of about
φ0.08 to 0.5 mm. The trenches 87 are formed by a router device, and
have widths of about 0.03 to 1 mm and depths of about 0.5 to 10 μm.
The second through holes 88 are formed by a drilling device and have
diameters of about φ0.1 to 1 mm. By the through holes 86, the
trenches 87, and the second through holes 88, a sufficient quantity of
cleaning liquid can also be spread on a gap between the frame 20 and the
printed circuit board 81 or between the frame 20 and the second printed
circuit board 84, and a flux residual adhering to an internal surface of
an electronic device 80 can be efficiently cleaned up.

[0052] The collective printed circuit board according to the present
invention can also be applied to an electronic device in which a
plurality of semiconductor elements and a plurality of electronic parts
are required to be mounted on both the major surfaces of, for example, a
printed circuit board. The embodiment will be described with reference to
FIG. 9. A frame connection pad 93 on an upper-surface end portion of a
printed circuit board 91 and the connection conductor 22 exposed from the
opening 23b on a lower-surface side of the frame 20 are bonded through a
conductive bonding material. Thereafter, a semiconductor element 92 and a
first electronic part 94 are mounted on a portion surrounded by the frame
20 on the upper-surface side of the printed circuit board 91 through a
conductive bonding material. An electrode 95 on a lower surface of the
printed circuit board 91 and a second electronic part 96 are mounted
through a conductive bonding material.

[0053] The connection conductor 22 exposed from the openings 23a on an
upper-surface side of the frame 20 is connected as an external connection
pad to an external electronic circuit board 97 through a conductive
bonding material. In this manner, the frame 20 is interposed between the
printed circuit board 91 and the external electronic circuit board 97 to
form a space in a position surrounded by the frame 20 on the
upper-surface side of the printed circuit board 91, and the semiconductor
element 92 and the first electronic part 94 can be mounted. Furthermore,
the second electronic part 96 is also mounted on a lower-surface side of
the printed circuit board 91. In this manner, a plurality of
semiconductor elements or electronic parts can be mounted on both the
major surfaces of the printed circuit board.

[0054] Another embodiment of a collective printed circuit board according
to the present invention will be described below with reference to FIG.
10. FIG. 10 is a schematic sectional view showing an example of an
embodiment of a printed circuit board 110 obtained from the collective
printed circuit board according to the present invention. The printed
circuit board 110 of the example includes a first printed circuit board
101 in which an electronic part is mounted on an upper-surface central
portion, a frame 102 bonded to an upper surface of the first printed
circuit board 101 to have an opening surrounding the electronic part, and
a second printed circuit board 103 bonded to an upper surface of the
frame 102 to close the opening. A third printed circuit board 104
including a layer configuration or a material different from that of the
frame 102 is bonded between the first printed circuit board 101 and the
second printed circuit board 103 on the internal side of the opening.

[0055] The first printed circuit board 101 is a high-density multi-layered
printed circuit board formed by, for example, a buildup method. An
electronic part E1 is mounted on an upper surface of the first printed
circuit board 101. A wiring conductor 105 including copper foil or a
copper-plated layer is arranged from an upper surface to a lower surface
of the first printed circuit board 101. A part of the wiring conductor
105 forms an electronic part connection pad 105a electrically connected
to the electronic part E1, an external connection pad 105b connected to
an external electronic circuit board, a connection pad 105c connected to
the frame 102, and a connection pad 105d connected to the third printed
circuit board 104. Since the wiring conductor 105 is partially formed by
the buildup method, for example, high density wires can be formed by very
thin wires each having a wire width and a wire interval of 20 μm or
less.

[0056] The frame 102, like the first printed circuit board 101, is a
high-density multi-layered printed circuit board formed by, for example,
the buildup method, and has an opening 102a surrounding the electronic
part E1 mounted on the first printed circuit board 101. A lower surface
of the frame is bonded to the first printed circuit board 101, and an
upper surface thereof is bonded to the second printed circuit board 103.
Like the first printed circuit board 101, a wiring conductor 106
including copper foil or a copper-plated layer is arranged from the upper
surface to the lower surface of the frame 102. A part of the wiring
conductor 106 forms a connection pad 106a connected to the first printed
circuit board 101 and a connection pad 106b connected to the second
printed circuit board 103.

[0057] Like the first printed circuit board 101 or the frame 102, the
second printed circuit board 103 is also a high-density multi-layered
printed circuit board formed by, for example, the buildup method. The
second printed circuit board 103 is bonded to the upper surface of the
frame 102 to close the opening 102a. An electronic part E2 is mounted on
an upper surface of the second printed circuit board 103. Also on the
second printed circuit board 103, a wiring conductor 107 including copper
foil or a copper-plated layer is arranged from an upper surface to a
lower surface of the second printed circuit board 103. A part of the
wiring conductor 107 forms an electronic part connection pad 107a
electrically connected to the electronic part E2 and a connection pad
107b connected to the frame 102.

[0058] The third printed circuit board 104 is formed by forming a through
hole 108 in, for example, a single-layered glass epoxy plate and has an
opening 104a surrounding the electronic part E1. A lower surface of the
third printed circuit board 104 is bonded to the first printed circuit
board 101, and an upper surface thereof is bonded to the second printed
circuit board 103. A wiring conductor 109 including copper foil or a
copper-plated layer is arranged from an upper surface to a lower surface
of the third printed circuit board 104 through a through hole 108. Apart
of the wiring conductor 109 forms a connection pad 109a connected to the
first printed circuit board 101 and a connection pad 109b connected to
the second printed circuit board 103. A diameter of the through hole 108
is a large diameter of about 100 to 300 μm. The connection pad 109a
and the connection pad 109b can be electrically connected to each other
with a low resistance through the large-diameter through hole 108.

[0059] The first printed circuit board 101 and the frame 102 and the third
printed circuit board 104 are connected to each other through solder
balls B, fixed to each other, and electrically connected to each other,
and the frame 102 and third printed circuit board 104 and the second
printed circuit board 103 are connected to each other through the solder
balls B, fixed to each other, and electrically connected to each other.
Since the frame 102 is a high-density multi-layered printed circuit board
formed by a buildup method, the frame 102 can high-density connect the
first printed circuit board 101 and the second printed circuit board 103
serving as the high-density printed circuit boards formed by the buildup
method like the frame 102 with a high density. Furthermore, the third
printed circuit board 104 can electrically connect the first printed
circuit board 101 and the second printed circuit board 103 through the
through hole 108 with a low resistance.

[0060] In this case, preferably for example, signal wires on the large
number of first printed circuit boards 101 and second printed circuit
boards 103 that are required to be connected are electrically connected
to each other through the high-density wiring conductor 106 of the frame
102, and the ground or power supply wires that require a large current
are electrically connected to each other through the low-resistance
wiring conductor 109 of the third printed circuit board 104. In this
manner, a large number of signals can be exchanged between the first
printed circuit board 101 and the second printed circuit board 103
through the wiring conductor 106, and the printed circuit board 110 that
can supply a sufficient ground voltage and a power supply voltage through
the wiring conductor 109 can be provided.

[0061] For example, when the third printed circuit board 104 is formed of
a material having good heat conductivity, for example, a highly heat
conductive metal such as copper or a highly heat conductive ceramic
material such as aluminum nitride, the first printed circuit board 101
and the second printed circuit board 103 can be connected to each other
with a low heat resistance, and heat from the electronic part E1 can be
efficiently radiated to the outside. Furthermore, when the third printed
circuit board 104 is formed by a high-rigidity material such as aluminum
nitride, for example, when buildup circuit boards that do not have core
circuit boards are used as the first printed circuit board 101, the frame
102, and the second printed circuit board 103, the composite printed
circuit board 110 that has less warpage or less deformation can be
provided.

[0062] In this manner, according to the composite printed circuit board
110 of the example, inside the opening of the frame 102 that bonds the
first printed circuit board 101 and the second printed circuit board 103
to each other, the third printed circuit board having a layer
configuration or a material different from that of frame 102 is arranged
to bond the first printed circuit board and the second printed circuit
board to each other and thus the first printed circuit board and the
second printed circuit board can be bonded to each other by extensive
connecting paths through the third printed circuit board and the frame.
For this reason, a degree of freedom of design increases, and a
multi-functional advanced composite printed circuit board 10 can be
provided.

[0063] The present invention is not limited to an example of the
embodiment described above. For example, as shown in FIG. 11, only the
inside of the third printed circuit board 104 may be partially sealed
with a sealing resin 111. In this case, the electronic part E1 can be
sealed with a small amount of sealing resin 111, and warpage to the
printed circuit board 110 by the sealing resin 111 can be reduced.

[0064] Furthermore, as shown in FIG. 12, on a side surface of the third
printed circuit board 104, for example, a chip capacitor 112 may be
arranged between the first printed circuit board 101 and the second
printed circuit board 103. In this case, the first printed circuit board
101 and the second printed circuit board 103 can be connected by the chip
capacitor 112 with a low resistance and a short path.

[0065] Furthermore, in an example of the embodiment described above, the
external frame 102 is formed by a high-density multi-layered printed
circuit board formed by a buildup method, and the internal third printed
circuit board 104 is formed by a single-layered glass epoxy plate.
However, the external frame 102 may be formed by a single-layered glass
epoxy plate, and the internal third printed circuit board 104 may be
formed by a high-density multi-layered printed circuit board obtained by
the buildup method.

[0066] An example of an embodiment of a collective printed circuit board
according to the present invention will be described below with reference
to FIG. 13. FIGS. 13A and 13B are schematic sectional views for
explaining an example of an embodiment of a printed circuit board
obtained from the collective printed circuit board according to the
present invention. The printed circuit board 210 includes a first printed
circuit board 201 in which the electronic part E1 is mounted on an
upper-surface central portion, a frame 202 bonded to an upper surface of
the first printed circuit board 201 to have an opening surrounding the
electronic part E1 through a solder bump, and the second printed circuit
board 203 bonded to an upper surface of the frame through a solder bump
to cover the opening of the frame 202.

[0067] The first printed circuit board 201 is a high-density multi-layered
printed circuit board formed by, for example, a buildup method. An
electronic part E1 is mounted on an upper surface of the first printed
circuit board 201. A wiring conductor (not shown) is arranged from an
upper surface to a lower surface of the first printed circuit board 201.

[0068] The frame 202, like the first printed circuit board 201, is a
high-density multi-layered printed circuit board formed by, for example,
the buildup method, and has an opening 202a surrounding the electronic
part E1 mounted on the first printed circuit board 201. A lower surface
of the frame is bonded to the first printed circuit board 201, and an
upper surface thereof is bonded to the second printed circuit board 203.
Like the first printed circuit board 201, a wiring conductor (not shown)
is arranged from the upper surface to the lower surface of the frame 202.

[0069] Like the first printed circuit board 201 or the frame 202, the
second printed circuit board 203 is also a high-density multi-layered
printed circuit board formed by, for example, the buildup method. The
second printed circuit board 203 is bonded to the upper surface of the
frame 202 to close the opening 202a. An electronic part E2 is formed on
an upper surface of the second printed circuit board 203. Also on the
second printed circuit board 203, a wiring conductor (not shown) is
arranged from the upper surface to the lower surface of the second
printed circuit board 203.

[0070] The first printed circuit board 201 and the frame 202 are bonded to
each other through the solder balls B, fixed to each other, and
electrically connected to each other, and the frame 202 and the second
printed circuit board 203 are bonded to each other through the solder
balls B, fixed to each other, and electrically connected to each other.

[0071] On the printed circuit board 210 of the example, a flow path 204
for a sealing resin is formed from the upper surface of the frame 202
between the frame 202 and the second printed circuit board 203 and
between the first printed circuit board 201 and the frame 202. The flow
path 204 is configured by a trench having, for example, a width of 200
μm and a depth of 30 μm, and is formed from an upper-surface outer
peripheral portion of the frame 202 between the first printed circuit
board 201 and the frame 202 through an inner wall of the opening 202a.

[0072] When a sealing resin 205 made of a liquid thermosetting resin is
discharged from a nozzle N into the flow path 204 on the upper surface of
the frame 202, the liquid sealing resin 205 passes through a flow path
204 by an operation of surface tension and flows from the upper surface
of the frame 202 into a portion between the frame 202 and the second
printed circuit board 203 and a portion between the first printed circuit
board 201 and the frame 202, and the portion between the frame 202 and
the second printed circuit board 203 and the portion between the first
printed circuit board 201 and the frame 202 are filled with the liquid
sealing resin 205. In this state, when the sealing resin 205 is
ultraviolet-cured or thermally cured, the frame 202 and the second
printed circuit board 203 are sealed with the cured sealing resin 205,
and the first printed circuit board 201 and the frame 202 are sealed with
the cured sealing resin 205.

[0073] In this manner, the flow path 204 for a sealing resin is formed
from the upper surface of the frame 202 to the portion between the frame
202 and the second printed circuit board 203 and the portion between the
first printed circuit board 201 and the frame 202, and the sealing resin
205 is caused to flow through the flow path 204 from the upper surface of
the frame 202 to the portion between the frame 202 and the second printed
circuit board 203 and the portion between the first printed circuit board
201 and the frame 202 to perform sealing. For this reason, filling of the
sealing resin 205 can be easily performed, and the printed circuit board
210 having good productivity can be provided.

[0074] The present invention is not limited to an example of the
embodiment of the present invention. For example, as shown in FIGS. 14A
and 14B, the flow path 204 for a sealing resin configured by a through
hole may be formed from the upper surface of the second printed circuit
board 203 to the portion between the frame 202 and the second printed
circuit board 203 and the portion between the first printed circuit board
201 and the frame 202. In this case also, the sealing resin 205 is caused
to flow through the flow path 204 from the upper surface of the second
printed circuit board 203 to the portion between the frame 202 and the
second printed circuit board 203 and the portion between the first
printed circuit board 201 and the frame 202 to perform sealing. For this
reason, filling of the sealing resin 205 can be easily performed, and a
printed circuit board 220 having good productivity can be provided. The
diameter of the through hole for forming the flow path 204 preferably
falls within the range of 200 to 1500 μm.

[0075] Furthermore, in the embodiment described above, the flow path 204
is formed by a trench or a through hole. However, the flow path 204 may
be formed by a combination of a trench and a through hole. Furthermore,
in place of the trench, a flow path 204 formed by a convex stripe may be
formed. Furthermore, a flow path guided from the portion between the
first printed circuit board 201 and the frame 202 to the portion between
the first printed circuit board 201 and the electronic part E1 may be
formed on an upper surface of the first printed circuit board 201. In
this case, the first printed circuit board 201 and the electronic part E1
can be simultaneously sealed.

[0076] The embodiments of the present invention have been described above.
However, the present invention is not limited to the embodiments, and
various changes and improvements can be made without departing from the
spirit and scope of the invention.